If you buy from Jameco, like I did, you have to buy the pins in sets of 10, so it comes out to be 1.90+1.50 +.80, or about 4.20$ total for the parts.

Time Required:
about 20-30 minutes...less if you have a hand crimper for these things, otherwise a pair of needle nose pliers works fine

Step 1.)

strip off 1/4" or a little less of the ends of 8x 3" pieces of wire. Twist it so it doesn't unravel. insert it into the end of one of the connectors (female or male) and either carefully use the pliers to bring down the edges of the terminal to secure the wire, or use your crimpers. then pinch the wire guide part of the connector. This should secure the wire in the connector fairly well, however I then used the super glue to secure it even better. Once done, push the connector all the way into the end of the housing. (Sorry I don't have any pictures of the steps involved here, was hard to do this and take pictures since the parts are so small)

Repeat 7 more times.

You should have this:

Step 2.)

Do the same as step 1, except with the male pins. You'll have to do this a little differently however for 3 of the pins (the ones that connect to the DEI harness).

You have two choices, you can either strip part of the wire mid way up the cable, or, if you used smaller gauge wire (24+) you can just twist your DEI wires in the end and insert into the connector) I used the mid-line method). I slid some shrink wrap tubing over the wire, and then once I twisted my DEI wires inline, I move the shrink wrap over and shrunk it.

The resulting harness will look like this:

Step 3.)

Install the harness into the alarm unit, and mount the sensor in the alarm tray in the open spot (it fits perfectly):

Hello, I'm assuming that no changes to / re-programming is required on installing the sensor?

I wonder if this is actually required as my car, without the shocksensor, when parked near a railway track starts beeping whenever a freight train passes by due to the vibration.

no reprogramming is required. I don't know why yours starts beeping, the factory alarm, at least on E90's doesn't have a shocksensor built in, at least not on most of the cars. This is why it's easy to add the DEI module. I built a harness to prevent having to cut any factory wires or use wire taps.

I just finished my install of the "D" sensor. I may have set it a bit too sensitive, but I wl see how I do with false alarms before I change anything. Thanks for a great DIY and a parts list!

Question: how can I confirm that the ultrasonic sensor is still working? The manual says all the windows including the moon roof must be closed for it to arm properly. How can you test the ultrasonic sensor with everything closed?

Also, it appears that double locking, which supposedly shuts down the ultrasonic and tilt sensors, does not affect this new shocksensor. I did the double lock, confirmed via the clown nose that it was in the other mode, but the shocksensor still set off the alarm when challenged. I was surprised as I though the sensor would do whatever the ultrasonic did. Perhaps the ultrasonic sensor does not power down, but somehow is simply ignored. I am unsure how a sensor in parallel on the same circuit can still set off the alarm but it does!

Update

The ultrasonic alarm does in fact arm even if the moonroof is left partially open. I tested it after a bit to let the ultrasonic get it's base reading. I just stuck my hand and arm in holding my iPhone. It went off. Interestingly it is hard to set off with just your hand, but stick a hard object in your hand and it goes off immediately. I guess the object reflects the sound waves better.

I just attempted to install it on my E90, the shocksensor light goes on but when i attempt to arm it or trigger it i get no sound from the siren. The following are some pics, anyone know what i might have dont wrong?